Is the Measles, Mumps, and Rubella (MMR) vaccine given in two doses?

MMR Vaccine Two-Dose Schedule

Yes, the MMR vaccine is routinely given as a two-dose series, with the first dose administered at 12-15 months of age and the second dose at 4-6 years of age. 1, 2

Standard Vaccination Schedule

Children

• First dose: Administer at age 12-15 months 3, 2
• Second dose: Administer at age 4-6 years (before kindergarten or first grade entry) 3, 2
• Minimum interval between doses: 28 days (4 weeks) 1, 2

This two-dose schedule has been jointly adopted by the Advisory Committee on Immunization Practices (ACIP), the American Academy of Pediatrics (AAP), and the American Academy of Family Physicians (AAFP). 3

Adults

• Persons born in 1957 or later: At least one dose of MMR vaccine is required unless they have documentation of vaccination or other acceptable evidence of immunity 3
• High-risk adults: Two doses are recommended for students in postsecondary institutions, healthcare personnel, international travelers, and household contacts of immunocompromised persons 4, 5
• Persons born before 1957: Generally considered immune and do not require vaccination 3

Rationale for Two Doses

The primary justification for the two-dose schedule is that approximately 5% of children fail to develop immunity after the first dose (primary vaccine failure). 3, 1 The second dose provides a second opportunity for immunization rather than addressing waning immunity, which is not a major cause of vaccine failure. 3

After two doses, at least 95% of recipients develop long-lasting immunity. 2

Special Circumstances

High-Risk Areas for Measles

• In counties with large inner-city populations, recent outbreaks, or more than five cases among preschool-aged children in the last 5 years, the first dose should be administered at 12 months (rather than waiting until 15 months). 3

International Travel

• Children ≥12 months: Should receive two doses separated by at least 28 days before departure 3
• Infants 6-11 months: Should receive one dose before departure, but this does not count toward the routine two-dose series and the child must be revaccinated with two doses starting at 12-15 months 3, 1, 2

Outbreak Settings

• During measles outbreaks, all persons at risk should have documentation of two doses given at least 1 month apart after the first birthday 1
• During mumps outbreaks specifically: A third dose may be recommended for persons at increased risk, but this is the only scenario where a third dose is indicated 1

HIV-Infected Persons

• MMR vaccination is recommended for all HIV-infected persons aged ≥12 months who do not have evidence of severe immunosuppression 3, 5
• The same two-dose schedule applies: first dose at 12-15 months and second dose at 4-6 years 5

Vaccine Interchangeability

Both available MMR vaccines in the United States (M-M-R II and PRIORIX) are fully interchangeable for all indications. 1, 2 Either vaccine can be used for any dose in the series without needing to restart or add extra doses.

Common Pitfalls to Avoid

• Do not restart the series if delayed: If a child is behind schedule, simply administer the missed doses at least 28 days apart—there is no need to restart regardless of time elapsed 2
• Do not count doses given before 12 months: Infants vaccinated before their first birthday (except in specific outbreak or travel situations) should be considered potentially susceptible and require the full two-dose series starting at 12 months 3
• Do not confuse mumps outbreak recommendations with routine care: A third dose is only indicated during mumps outbreaks for high-risk individuals, not for routine measles or rubella protection 1